A variety of packages, including dispensing packages or containers, have been developed for household products, personal care products, and other products. Containers that have a pleasing aesthetic look to consumers have a closure design that is fully integrated with the design of the container. This conveys the message that the integration of the two components was well thought of. This is important to make closure functioning intuitive to consumers. An example of a well integrated container/closure system is one where the container's geometry wraps around the closure to create shoulders. This geometry can also be referred to as a container with a recessed neck. This recess geometry serves different purposes: overall integrated look to the container and closure, stability to container in inverted orientation, and makes functioning of closure more intuitive to consumers.
Blowing this container geometry with today's traditional blow molding technology is not possible, as the container would have undercuts in the concave portion of the shoulder. This is because when the molding cavity tools are to be opened, the steel creating the concave part becomes trapped. If one were to shape the top part using the blow pin head tool, one would then encounter an undercut under the snap bead feature that is in proximity to the container's shoulder. This is because one would not be able to pull the blow pin tooling which creates the snap bead from underneath the formed bead feature.
When looking at containers in the market that use a recess geometry design, it has been noticed that they usually have a straight shoulder vs. a concave design. The forming of that recess does not require any inventive step as there is at least one direction in which the mold can open with a straight-pull motion without yielding to any mold material becoming trapped within the container's geometry. Yet, recess geometries that can be unmolded with a straight-pull in a blow mold are highly restricted in design, limiting the integration of the closure with the blown container and therefore all the benefits stated above.
There are other containers currently in the market that have different shoulder geometries, but these containers use a different neck from what the present invention has found. These containers use a closure attachment mechanism, where the closure snaps onto the container from the inside of the dispensing orifice. A non-limiting example of a container made through the process described in the present invention can be referred to as having a snap-on closure mechanism, where the closure snaps onto the outside of the container's neck. From the present invention discovery, the present design provides more reliability against leaking, as the outside part of the neck is calibrated, providing tighter tolerances, than the inside part of the container. The inside of the container is not highly calibrated, increasing the probability of poor engagement between container and closure, and thus leading to potential leaking. This is because the parts blown via the extrusion blow molding process usually have better controlled geometry on the outside of the part rather than the inside, as the material wall thickness can vary due to part aspect ratios translating into differing parison stretch ratios in both radial and axial directions. In addition, containers whose closures attach onto the container from the inside of the neck usually require trimming and reaming of the neck as secondary operations. An operation that cuts-away excess material is inherently not cost-effective and should be avoided. Furthermore, any cutting operation requires straight access to the part that shall be cut away restricting the available recess geometry and limiting the integration of the closure with the blown container and therefore all the benefits stated above. With a closure attachment mechanism where the closure seals from the inside of the neck and snaps onto the container from the outside of the neck, a traditional striker plate and blow pin tool design can be used, where the blow pin cuts the parison when it comes in contact with the striker plate, creating a calibrated neck and therefore eliminating the need for secondary operations such as trimming and reaming.
Currently, most closures complete the geometry of the container, thereby requiring the size of the closure to be proportional to the geometry of the container. In the present invention, the size of the closure is minimized thereby providing several benefits. One of the benefits is reducing the weight of the closure to the minimum amount of resin needed to enable the required closure functionality. This is a benefit for the environment as industry currently does not have a well established polypropylene recycling stream. By having a closure that has a reduced weight from the overall package, this allows a container to have improved recyclability. It also reduces the overall costs of the closure including costs associated with resin, processing, tooling, injection mold (IM) press selection, and others. Another benefit of minimizing closure size is that the closure becomes a less focal point of the design making it more inductive to use the same closure for different container designs within one brand and even enable the use of the same closure across different brands/shaped families. This drives optimization and efficiency and in return reduces further costs. This further enables the silhouette of the shape to be scaled proportionally without the use of additional features such as steps, larger radii or other geometric alterations and angles to accommodate the closure.
Another benefit for minimizing the closure size is that it can be integrated in the container shape. When the container is in its inverted orientation, an integrated design allows the use of the container top surface to add stability vs. requiring a larger closure. It also aids in creating differentiation between the forms (such as shampoo and conditioner), helping consumers identify the product that they are looking for. This drives scale in the container design and development and therefore is an advantage. A further advantage is that having a recessed closure provides a higher level of protection from damage due to the recessed closure being protected by the recess geometry. Another benefit of having a recessed neck where the container wraps around the closure is that it enables using the same closure across different sizes while still having an integrated look between the container and the closure. A further benefit of the present invention is the enablement of using the same closure across containers made by different molding technologies. Non-limiting examples of molding technologies include extrusion blow molding (EBM), injection blow molding (IBM), and injection stretch blow molding (ISBM). This drives scale and further reduces costs.
Although inserts moving inside molds to release undercuts are known in the industry, these are in general for parts made via the injection molding process and not via the blow molding platforms, as the present invention has found. Although moving insert components can be used inside extrusion blow molding molds, they are traditionally used to permanently deform the blown parts to create special features, such as lips or to create spaces to which appendages, such as handles are permanently attached. The present invention enables releasing undercuts created by having a recessed neck geometry, coupled with a closure attachment mechanism that is integral to the outside of the container's neck.
It is an objective of the present invention to provide a blowing process to create a recess in a blown container. Such a recess allows integration of the closure with the container such that when the closure is coupled with the blown container, it is substantially flush to the apex of the outmost surface of that blown container.